Shaft for roller wheel

Abstract

The invention provides a shaft for a roller wheel which is excellent in strength and can achieve a weight saving. The invention provides a shaft for a roller wheel which rotatably supports a roller ( 3 ) outward fitted between both end portions ( 5 a, 5 b ) in a state in which both end portions ( 5 a, 5 b ) are fixed, and receives a load in a diametrical direction via the roller ( 3 ). Recess portions ( 6, 6 ) are provided on a side to which the load is not applied, on an outer peripheral surface corresponding to the roller ( 3 ). The load applying direction is a vertical direction. A cross sectional shape of the shaft in the recess portions ( 6, 6 ) is formed in a shape which is constituted by an upper circular arc portion ( 10 ) on an upper side, a lower circular arc portion ( 11 ) on a lower side, and a vertical connection portion ( 12 ) passing through a shaft axis (O) and connecting the upper circular arc portion ( 10 ) to the lower circular arc portion ( 11 ).

1. A shaft for rotatably supporting a roller wheel, the shaft comprising:
 end portions having the roller fitted therebetween; and 
 a middle portion having the roller fitted thereon, the middle portion having a connection portion that extends along a diametrical direction of the shaft and further having recess portions at symmetrical positions with respect to a shaft axis, 
 wherein the shaft receives a load from the roller along the diametrical direction of the shaft, and 
 wherein the cross-section of the middle portion of the shaft includes an upper portion and a lower portion each of which receives the load from the roller, and the connection portion connecting the upper and lower portions. 
 
   
   
     2. The shaft as in  claim 1 , wherein the diametrical direction to which the shaft receives the load from the roller is a vertical direction, and wherein the connection portion extends vertically and passes through the shaft axis. 
   
   
     3. The shaft as in  claim 1 , wherein each of the recess portions of the middle portion of the shaft has an opening that extends horizontally from the vertically extending connection portion, the opening becoming smaller as it extends toward the end portions of the shaft.